nfssvc.c

Go to the documentation of this file.

/*
 * Central processing for nfsd.
 *
 * Authors: Olaf Kirch ([email protected])
 *
 * Copyright (C) 1995, 1996, 1997 Olaf Kirch <[email protected]>
 */

#include <linux/sched.h>
#include <linux/freezer.h>
#include <linux/module.h>
#include <linux/fs_struct.h>
#include <linux/swap.h>
#include <linux/nsproxy.h>

#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/lockd/bind.h>
#include <linux/nfsacl.h>
#include <linux/seq_file.h>
#include <net/net_namespace.h>
#include "nfsd.h"
#include "cache.h"
#include "vfs.h"

#define NFSDDBG_FACILITY    NFSDDBG_SVC

extern struct svc_program   nfsd_program;
static int          nfsd(void *vrqstp);
struct timeval          nfssvc_boot;

/*
 * nfsd_mutex protects nfsd_serv -- both the pointer itself and the members
 * of the svc_serv struct. In particular, ->sv_nrthreads but also to some
 * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt
 *
 * If (out side the lock) nfsd_serv is non-NULL, then it must point to a
 * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0. That number
 * of nfsd threads must exist and each must listed in ->sp_all_threads in each
 * entry of ->sv_pools[].
 *
 * Transitions of the thread count between zero and non-zero are of particular
 * interest since the svc_serv needs to be created and initialized at that
 * point, or freed.
 *
 * Finally, the nfsd_mutex also protects some of the global variables that are
 * accessed when nfsd starts and that are settable via the write_* routines in
 * nfsctl.c. In particular:
 *
 *  user_recovery_dirname
 *  user_lease_time
 *  nfsd_versions
 */
DEFINE_MUTEX(nfsd_mutex);
struct svc_serv         *nfsd_serv;

/*
 * nfsd_drc_lock protects nfsd_drc_max_pages and nfsd_drc_pages_used.
 * nfsd_drc_max_pages limits the total amount of memory available for
 * version 4.1 DRC caches.
 * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage.
 */
spinlock_t  nfsd_drc_lock;
unsigned int    nfsd_drc_max_mem;
unsigned int    nfsd_drc_mem_used;

#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
static struct svc_stat  nfsd_acl_svcstats;
static struct svc_version * nfsd_acl_version[] = {
    [2] = &nfsd_acl_version2,
    [3] = &nfsd_acl_version3,
};

#define NFSD_ACL_MINVERS            2
#define NFSD_ACL_NRVERS     ARRAY_SIZE(nfsd_acl_version)
static struct svc_version *nfsd_acl_versions[NFSD_ACL_NRVERS];

static struct svc_program   nfsd_acl_program = {
    .pg_prog        = NFS_ACL_PROGRAM,
    .pg_nvers       = NFSD_ACL_NRVERS,
    .pg_vers        = nfsd_acl_versions,
    .pg_name        = "nfsacl",
    .pg_class       = "nfsd",
    .pg_stats       = &nfsd_acl_svcstats,
    .pg_authenticate    = &svc_set_client,
};

static struct svc_stat  nfsd_acl_svcstats = {
    .program    = &nfsd_acl_program,
};
#endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */

static struct svc_version * nfsd_version[] = {
    [2] = &nfsd_version2,
#if defined(CONFIG_NFSD_V3)
    [3] = &nfsd_version3,
#endif
#if defined(CONFIG_NFSD_V4)
    [4] = &nfsd_version4,
#endif
};

#define NFSD_MINVERS        2
#define NFSD_NRVERS     ARRAY_SIZE(nfsd_version)
static struct svc_version *nfsd_versions[NFSD_NRVERS];

struct svc_program      nfsd_program = {
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
    .pg_next        = &nfsd_acl_program,
#endif
    .pg_prog        = NFS_PROGRAM,      /* program number */
    .pg_nvers       = NFSD_NRVERS,      /* nr of entries in nfsd_version */
    .pg_vers        = nfsd_versions,    /* version table */
    .pg_name        = "nfsd",       /* program name */
    .pg_class       = "nfsd",       /* authentication class */
    .pg_stats       = &nfsd_svcstats,   /* version table */
    .pg_authenticate    = &svc_set_client,  /* export authentication */

};

u32 nfsd_supported_minorversion;

int nfsd_vers(int vers, enum vers_op change)
{
    if (vers < NFSD_MINVERS || vers >= NFSD_NRVERS)
        return 0;
    switch(change) {
    case NFSD_SET:
        nfsd_versions[vers] = nfsd_version[vers];
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
        if (vers < NFSD_ACL_NRVERS)
            nfsd_acl_versions[vers] = nfsd_acl_version[vers];
#endif
        break;
    case NFSD_CLEAR:
        nfsd_versions[vers] = NULL;
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
        if (vers < NFSD_ACL_NRVERS)
            nfsd_acl_versions[vers] = NULL;
#endif
        break;
    case NFSD_TEST:
        return nfsd_versions[vers] != NULL;
    case NFSD_AVAIL:
        return nfsd_version[vers] != NULL;
    }
    return 0;
}

int nfsd_minorversion(u32 minorversion, enum vers_op change)
{
    if (minorversion > NFSD_SUPPORTED_MINOR_VERSION)
        return -1;
    switch(change) {
    case NFSD_SET:
        nfsd_supported_minorversion = minorversion;
        break;
    case NFSD_CLEAR:
        if (minorversion == 0)
            return -1;
        nfsd_supported_minorversion = minorversion - 1;
        break;
    case NFSD_TEST:
        return minorversion <= nfsd_supported_minorversion;
    case NFSD_AVAIL:
        return minorversion <= NFSD_SUPPORTED_MINOR_VERSION;
    }
    return 0;
}

/*
 * Maximum number of nfsd processes
 */
#define NFSD_MAXSERVS       8192

int nfsd_nrthreads(void)
{
    int rv = 0;
    mutex_lock(&nfsd_mutex);
    if (nfsd_serv)
        rv = nfsd_serv->sv_nrthreads;
    mutex_unlock(&nfsd_mutex);
    return rv;
}

static int nfsd_init_socks(void)
{
    int error;
    if (!list_empty(&nfsd_serv->sv_permsocks))
        return 0;

    error = svc_create_xprt(nfsd_serv, "udp", &init_net, PF_INET, NFS_PORT,
                    SVC_SOCK_DEFAULTS);
    if (error < 0)
        return error;

    error = svc_create_xprt(nfsd_serv, "tcp", &init_net, PF_INET, NFS_PORT,
                    SVC_SOCK_DEFAULTS);
    if (error < 0)
        return error;

    return 0;
}

static bool nfsd_up = false;

static int nfsd_startup(int nrservs)
{
    int ret;

    if (nfsd_up)
        return 0;
    /*
     * Readahead param cache - will no-op if it already exists.
     * (Note therefore results will be suboptimal if number of
     * threads is modified after nfsd start.)
     */
    ret = nfsd_racache_init(2*nrservs);
    if (ret)
        return ret;
    ret = nfsd_init_socks();
    if (ret)
        goto out_racache;
    ret = lockd_up(&init_net);
    if (ret)
        goto out_racache;
    ret = nfs4_state_start();
    if (ret)
        goto out_lockd;
    nfsd_up = true;
    return 0;
out_lockd:
    lockd_down(&init_net);
out_racache:
    nfsd_racache_shutdown();
    return ret;
}

static void nfsd_shutdown(void)
{
    /*
     * write_ports can create the server without actually starting
     * any threads--if we get shut down before any threads are
     * started, then nfsd_last_thread will be run before any of this
     * other initialization has been done.
     */
    if (!nfsd_up)
        return;
    nfs4_state_shutdown();
    lockd_down(&init_net);
    nfsd_racache_shutdown();
    nfsd_up = false;
}

static void nfsd_last_thread(struct svc_serv *serv, struct net *net)
{
    nfsd_shutdown();

    svc_rpcb_cleanup(serv, net);

    printk(KERN_WARNING "nfsd: last server has exited, flushing export "
                "cache\n");
    nfsd_export_flush(net);
}

void nfsd_reset_versions(void)
{
    int found_one = 0;
    int i;

    for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++) {
        if (nfsd_program.pg_vers[i])
            found_one = 1;
    }

    if (!found_one) {
        for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++)
            nfsd_program.pg_vers[i] = nfsd_version[i];
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
        for (i = NFSD_ACL_MINVERS; i < NFSD_ACL_NRVERS; i++)
            nfsd_acl_program.pg_vers[i] =
                nfsd_acl_version[i];
#endif
    }
}

/*
 * Each session guarantees a negotiated per slot memory cache for replies
 * which in turn consumes memory beyond the v2/v3/v4.0 server. A dedicated
 * NFSv4.1 server might want to use more memory for a DRC than a machine
 * with mutiple services.
 *
 * Impose a hard limit on the number of pages for the DRC which varies
 * according to the machines free pages. This is of course only a default.
 *
 * For now this is a #defined shift which could be under admin control
 * in the future.
 */
static void set_max_drc(void)
{
    #define NFSD_DRC_SIZE_SHIFT 10
    nfsd_drc_max_mem = (nr_free_buffer_pages()
                    >> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE;
    nfsd_drc_mem_used = 0;
    spin_lock_init(&nfsd_drc_lock);
    dprintk("%s nfsd_drc_max_mem %u \n", __func__, nfsd_drc_max_mem);
}

static int nfsd_get_default_max_blksize(void)
{
    struct sysinfo i;
    unsigned long long target;
    unsigned long ret;

    si_meminfo(&i);
    target = (i.totalram - i.totalhigh) << PAGE_SHIFT;
    /*
     * Aim for 1/4096 of memory per thread This gives 1MB on 4Gig
     * machines, but only uses 32K on 128M machines.  Bottom out at
     * 8K on 32M and smaller.  Of course, this is only a default.
     */
    target >>= 12;

    ret = NFSSVC_MAXBLKSIZE;
    while (ret > target && ret >= 8*1024*2)
        ret /= 2;
    return ret;
}

int nfsd_create_serv(void)
{
    int error;
    struct net *net = current->nsproxy->net_ns;

    WARN_ON(!mutex_is_locked(&nfsd_mutex));
    if (nfsd_serv) {
        svc_get(nfsd_serv);
        return 0;
    }
    if (nfsd_max_blksize == 0)
        nfsd_max_blksize = nfsd_get_default_max_blksize();
    nfsd_reset_versions();
    nfsd_serv = svc_create_pooled(&nfsd_program, nfsd_max_blksize,
                      nfsd_last_thread, nfsd, THIS_MODULE);
    if (nfsd_serv == NULL)
        return -ENOMEM;

    error = svc_bind(nfsd_serv, net);
    if (error < 0) {
        svc_destroy(nfsd_serv);
        return error;
    }

    set_max_drc();
    do_gettimeofday(&nfssvc_boot);      /* record boot time */
    return 0;
}

int nfsd_nrpools(void)
{
    if (nfsd_serv == NULL)
        return 0;
    else
        return nfsd_serv->sv_nrpools;
}

int nfsd_get_nrthreads(int n, int *nthreads)
{
    int i = 0;

    if (nfsd_serv != NULL) {
        for (i = 0; i < nfsd_serv->sv_nrpools && i < n; i++)
            nthreads[i] = nfsd_serv->sv_pools[i].sp_nrthreads;
    }

    return 0;
}

int nfsd_set_nrthreads(int n, int *nthreads)
{
    int i = 0;
    int tot = 0;
    int err = 0;
    struct net *net = &init_net;

    WARN_ON(!mutex_is_locked(&nfsd_mutex));

    if (nfsd_serv == NULL || n <= 0)
        return 0;

    if (n > nfsd_serv->sv_nrpools)
        n = nfsd_serv->sv_nrpools;

    /* enforce a global maximum number of threads */
    tot = 0;
    for (i = 0; i < n; i++) {
        if (nthreads[i] > NFSD_MAXSERVS)
            nthreads[i] = NFSD_MAXSERVS;
        tot += nthreads[i];
    }
    if (tot > NFSD_MAXSERVS) {
        /* total too large: scale down requested numbers */
        for (i = 0; i < n && tot > 0; i++) {
                int new = nthreads[i] * NFSD_MAXSERVS / tot;
            tot -= (nthreads[i] - new);
            nthreads[i] = new;
        }
        for (i = 0; i < n && tot > 0; i++) {
            nthreads[i]--;
            tot--;
        }
    }

    /*
     * There must always be a thread in pool 0; the admin
     * can't shut down NFS completely using pool_threads.
     */
    if (nthreads[0] == 0)
        nthreads[0] = 1;

    /* apply the new numbers */
    svc_get(nfsd_serv);
    for (i = 0; i < n; i++) {
        err = svc_set_num_threads(nfsd_serv, &nfsd_serv->sv_pools[i],
                          nthreads[i]);
        if (err)
            break;
    }
    nfsd_destroy(net);
    return err;
}

/*
 * Adjust the number of threads and return the new number of threads.
 * This is also the function that starts the server if necessary, if
 * this is the first time nrservs is nonzero.
 */
int
nfsd_svc(int nrservs)
{
    int error;
    bool    nfsd_up_before;
    struct net *net = &init_net;

    mutex_lock(&nfsd_mutex);
    dprintk("nfsd: creating service\n");
    if (nrservs <= 0)
        nrservs = 0;
    if (nrservs > NFSD_MAXSERVS)
        nrservs = NFSD_MAXSERVS;
    error = 0;
    if (nrservs == 0 && nfsd_serv == NULL)
        goto out;

    error = nfsd_create_serv();
    if (error)
        goto out;

    nfsd_up_before = nfsd_up;

    error = nfsd_startup(nrservs);
    if (error)
        goto out_destroy;
    error = svc_set_num_threads(nfsd_serv, NULL, nrservs);
    if (error)
        goto out_shutdown;
    /* We are holding a reference to nfsd_serv which
     * we don't want to count in the return value,
     * so subtract 1
     */
    error = nfsd_serv->sv_nrthreads - 1;
out_shutdown:
    if (error < 0 && !nfsd_up_before)
        nfsd_shutdown();
out_destroy:
    nfsd_destroy(net);      /* Release server */
out:
    mutex_unlock(&nfsd_mutex);
    return error;
}


/*
 * This is the NFS server kernel thread
 */
static int
nfsd(void *vrqstp)
{
    struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
    int err;

    /* Lock module and set up kernel thread */
    mutex_lock(&nfsd_mutex);

    /* At this point, the thread shares current->fs
     * with the init process. We need to create files with a
     * umask of 0 instead of init's umask. */
    if (unshare_fs_struct() < 0) {
        printk("Unable to start nfsd thread: out of memory\n");
        goto out;
    }

    current->fs->umask = 0;

    /*
     * thread is spawned with all signals set to SIG_IGN, re-enable
     * the ones that will bring down the thread
     */
    allow_signal(SIGKILL);
    allow_signal(SIGHUP);
    allow_signal(SIGINT);
    allow_signal(SIGQUIT);

    nfsdstats.th_cnt++;
    mutex_unlock(&nfsd_mutex);

    /*
     * We want less throttling in balance_dirty_pages() so that nfs to
     * localhost doesn't cause nfsd to lock up due to all the client's
     * dirty pages.
     */
    current->flags |= PF_LESS_THROTTLE;
    set_freezable();

    /*
     * The main request loop
     */
    for (;;) {
        /*
         * Find a socket with data available and call its
         * recvfrom routine.
         */
        while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
            ;
        if (err == -EINTR)
            break;
        validate_process_creds();
        svc_process(rqstp);
        validate_process_creds();
    }

    /* Clear signals before calling svc_exit_thread() */
    flush_signals(current);

    mutex_lock(&nfsd_mutex);
    nfsdstats.th_cnt --;

out:
    rqstp->rq_server = NULL;

    /* Release the thread */
    svc_exit_thread(rqstp);

    nfsd_destroy(&init_net);

    /* Release module */
    mutex_unlock(&nfsd_mutex);
    module_put_and_exit(0);
    return 0;
}

static __be32 map_new_errors(u32 vers, __be32 nfserr)
{
    if (nfserr == nfserr_jukebox && vers == 2)
        return nfserr_dropit;
    if (nfserr == nfserr_wrongsec && vers < 4)
        return nfserr_acces;
    return nfserr;
}

int
nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
{
    struct svc_procedure    *proc;
    kxdrproc_t      xdr;
    __be32          nfserr;
    __be32          *nfserrp;

    dprintk("nfsd_dispatch: vers %d proc %d\n",
                rqstp->rq_vers, rqstp->rq_proc);
    proc = rqstp->rq_procinfo;

    /*
     * Give the xdr decoder a chance to change this if it wants
     * (necessary in the NFSv4.0 compound case)
     */
    rqstp->rq_cachetype = proc->pc_cachetype;
    /* Decode arguments */
    xdr = proc->pc_decode;
    if (xdr && !xdr(rqstp, (__be32*)rqstp->rq_arg.head[0].iov_base,
            rqstp->rq_argp)) {
        dprintk("nfsd: failed to decode arguments!\n");
        *statp = rpc_garbage_args;
        return 1;
    }

    /* Check whether we have this call in the cache. */
    switch (nfsd_cache_lookup(rqstp)) {
    case RC_INTR:
    case RC_DROPIT:
        return 0;
    case RC_REPLY:
        return 1;
    case RC_DOIT:;
        /* do it */
    }

    /* need to grab the location to store the status, as
     * nfsv4 does some encoding while processing 
     */
    nfserrp = rqstp->rq_res.head[0].iov_base
        + rqstp->rq_res.head[0].iov_len;
    rqstp->rq_res.head[0].iov_len += sizeof(__be32);

    /* Now call the procedure handler, and encode NFS status. */
    nfserr = proc->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
    nfserr = map_new_errors(rqstp->rq_vers, nfserr);
    if (nfserr == nfserr_dropit || rqstp->rq_dropme) {
        dprintk("nfsd: Dropping request; may be revisited later\n");
        nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
        return 0;
    }

    if (rqstp->rq_proc != 0)
        *nfserrp++ = nfserr;

    /* Encode result.
     * For NFSv2, additional info is never returned in case of an error.
     */
    if (!(nfserr && rqstp->rq_vers == 2)) {
        xdr = proc->pc_encode;
        if (xdr && !xdr(rqstp, nfserrp,
                rqstp->rq_resp)) {
            /* Failed to encode result. Release cache entry */
            dprintk("nfsd: failed to encode result!\n");
            nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
            *statp = rpc_system_err;
            return 1;
        }
    }

    /* Store reply in cache. */
    nfsd_cache_update(rqstp, proc->pc_cachetype, statp + 1);
    return 1;
}

int nfsd_pool_stats_open(struct inode *inode, struct file *file)
{
    int ret;
    mutex_lock(&nfsd_mutex);
    if (nfsd_serv == NULL) {
        mutex_unlock(&nfsd_mutex);
        return -ENODEV;
    }
    /* bump up the psudo refcount while traversing */
    svc_get(nfsd_serv);
    ret = svc_pool_stats_open(nfsd_serv, file);
    mutex_unlock(&nfsd_mutex);
    return ret;
}

int nfsd_pool_stats_release(struct inode *inode, struct file *file)
{
    int ret = seq_release(inode, file);
    struct net *net = &init_net;

    mutex_lock(&nfsd_mutex);
    /* this function really, really should have been called svc_put() */
    nfsd_destroy(net);
    mutex_unlock(&nfsd_mutex);
    return ret;
}